Maybe here, but not all over the world. Oil is traded in U.S. dollars, so countries like China and Canada that are out there working to reduce their exchange rates in an attempt to protect their domestic economies may not actually see the lower prices. When the Canadian dollar was strong a few years ago, the price of gasoline in the two countries was very similar. Now that the Canadian dollar is weak, their gasoline prices are still high while U.S. prices are dropping steeply.
Look, I am all for tariffs to protect industry so if you want to propose a floating tariff to keep oil at $40.00 a bbl ( gas around $2.00/gal) I am all for it. The tariff would go away once oil went above $40.00. But you say the word tariff around here and it is like throwing Holy water on a vampire.